How to solve the problem that the brake cylinder does not return

First of all, it is recommended that you check whether the piston of the brake cylinder is stuck due to dirt. There is another possibility that the brake cylinder cannot be returned to the position due to the phenomenon that the pipe fixing the brake cylinder is stuck. The conduit is the part where the brake cylinder and the suspension are fixed, outside the fixing screws of the brake cylinder and the suspension, that is, in the holes of the two mounting bolts of the brake cylinder. You can remove the brake cylinder, remove the conduit, sand it with fine sandpaper, apply butter, and put the cylinder back in the vehicle.